Wind power plants of this type are suitable for covering a portion of the power that is required by all consumers. In the future, they will also serve to generate hydrogen, in addition to oxygen, through hydrolysis of water. Through electricity generated by means of fuel cells in motor vehicles, the hydrogen will replace the existing types of vehicle fuel: gasoline, diesel or natural gas. Furthermore, for countries currently producing petroleum and natural gas, which are at present not living with a high level of technology, the installation of large-scale wind power plants with greater capacity, inter alia, based on earnings from their petroleum and natural gas business, is an important issue with respect to securing and improving their future existence when the natural resources are exhausted.
Worldwide, windmills with a horizontal axis have become widespread. Most of them have three rotor blades or rotor vanes fastened to the rotor which subsequently delivers the energy generated by wind power to a small nacelle with gear box, braking device, generator and control devices. These installations are supported on towers by means of a slew ring and are operated via control equipment.
Due to an overproduction of electricity from nuclear power plants and fossil fuel plants, the current three-blade wind power plants are only exploited to a small extent which means they are temporarily switched off at the request of power distribution companies, although there is sufficient wind energy available. Already today, it would be necessary to collect the entire energy available from wind power plants, keep it for a certain time in storage-type facilities or convert it into energy carriers such as hydrogen. Current procedures are likely to become obsolete with the introduction of large-scale wind power plants. In view of the imminent end of the world's carbon and hydrocarbon resources, the use of carbon, petroleum and natural gas for thermal utilization, also in motor vehicles, should urgently be prohibited by global conventions ahead of time, and this prohibition should actually be enforced so the international chemical and metallurgical industry will have these important resources at its disposal for a longer period of time. Not till then will electricity from alternative and renewable energies become the most important source of electricity. Large-scale wind power plants of a size mentioned above can serve as an important pillar of support in the reorganization of global energy consumption and its implementation.
Although the wind power plants presently existing in Germany generate a considerable amount of electric energy, the portion of electricity that is obtained from alternative energy sources (wind, water, sun) accounts, on aggregate, for as little as 10% of total national power consumption.
With three-blade wind power plants according to the state-of-the-art, a disadvantage has become obvious: these three-blade wind power plants provide poor performance because their blades make use of an area exposed to the wind which is as small as approximately 60 m2. Also their performance is limited by the circular area that is covered by the blades. The wind power plant setups which have been in use up to now impose restrictions on blade length and, hence, on the covered circular area, because the blade materials employed imply a certain maximum permitted strain level.
Within the state of the art one approach to a solution of this problem is found, which consists in enhancing the performance of the three-blade wind power plants by enlarging the rotor blade dimensions in length and width.
However, this approach has exposed a disadvantage inasmuch as currently available composite materials such as glass fibers and synthetic resin do not permit a significant increase in the dimensions of the rotor blades, because an increase in weight will compete against the requirements with respect to stability, thus adversely affecting or even excluding stability. The alternative of broadening the rotor blades in those zones where, according to the state of the art, they exhibit a more pointed shape in order to increase the wind absorption capacity equally fails to meet stability requirements, because a considerable increase in weight must be expected also in this case.
It is therefore the task of the present invention to create a wind power plant having an enhanced performance as a result of a greater absorption of wind power than those provided by current state-of-the-art approaches.
According to the invention, this task is accomplished by a wind turbine with the features of patent claim 1. Accordingly, the wind turbine comprises:                a stator;        a rotor, which is supported by the stator;        a circular guide device, which has a plurality of fastening points provided on the circumference;        at least two rotor blades, each of which is rotatably supported at its proximal end on the rotor and at its distal end by the circular guide device, and        a plurality of tensioning ropes, which under tension connect the fastening points of the circular guide device to the stator for stably holding the circular guide device in a position that is concentric to the rotor.        
A strong bearing section is created for the distal end of the rotor blades or rotor blade heads which are rotatably supported to allow rotation along a circular path around the rotor unit. This additional support of the distal ends of the rotor blades by means of a circular or annular guide device or ring support element allows to design the individual rotor blades with a greater length, which is, without restricting the scope of the subject-matter to be protected, expected to be twice the length of approximately 100 m or longer, with greater width and increased weight. Moreover, several rotor blades with narrowed proximal ends can be connected to the rotor unit, because, unlike state-of-the-art devices, the rotor unit does not have to carry the whole weight of the rotor blades, and hence a tapered bearing section is sufficient. Because the rotor blade ends are movably supported and guided along a circular path by the stationary circular guide device, the forces of the individual rotor blades are transmitted to the rotor axis as a torque and—amongst other possibilities—can be transformed into an electric current by a generator in the nacelle. As an additional option, a greater number of rotor blades than typically three at present may be installed on this wind power plant. Furthermore, the width of the state-of-the-art tapered distal ends of the rotor blades can be enlarged.
The guide device is kept in a concentric position in relation to the rotor axis by the plurality of tensioning ropes. The forces acting on the guide device in a direction parallel to the rotor axis, are transferred to the stator via the plurality of tensioning ropes.
In one embodiment of the invention, the stator comprises at least one first securing anchor in the direction of an axis of the rotor in front of the rotor blades and at least one second securing anchor in the direction of the axis of the rotor behind the rotor blades and a first subset of the plurality of tensioning ropes is attachable to the at least one first securing anchor and a second subset of the plurality of tensioning ropes is attachable to the at least one second securing anchor.
In another embodiment, the wind turbine is provided comprising a nacelle casing that forms part of the stator, wherein the at least one first securing anchor is arranged on the nacelle casing.
According to a further advancement, the wind turbine comprises a body forming part of the stator and supported on the rotor in a freely rotatable manner, wherein the at least one second securing anchor is arranged on the body.
In one embodiment, the nacelle is pivot-mounted for swivel motion in the horizontal plane.
The nacelle may be mounted on a column.
One embodiment provides for a trolley body arranged at the distal end of the rotor blades, which runs in a circular guide device.
According to a further advancement, the trolley body comprises at least one rolling body on its surface that is supported on the circular guide device.
The circular guide device may be conceived as a ring-shaped hollow rail configuration that encloses the trolley body.
In one embodiment, the trolley body is connected under tension with the distal end of the rotor blades via an elastic mounting suspension, and the tension force which is applied to a rotor blade by the elastic mounting suspension is adjustable.
According to a further advancement, the trolley body is composed of several trays comprising ball-bearing cages and arranged in a fashion such as to be mutually shifted in the axial direction.
In one embodiment, the elastic mounting suspension is provided in a manner to be coupled to an axis that supports ball-bearing cage trays which are arranged such as to be mutually shifted in the axial direction.
Each ball-bearing cage tray may comprise several rolling bodies supported on its outer surface.
Identical reference numerals in the figures of the drawings designate identical components or components of identical function.